The age of energy-sucking, carbon-emitting concrete is still upon us, but more sustainable building materials are beginning to emerge. Fungi are among them. The latest development in that area is mycocrete, a fungal paste that can be injected into textile molds. That may not sound particularly appetizing, but then again neither is concrete. After all, buildings are meant to be used, not eaten.
Sustainable Buildings From Fungi: The Building Block Method
Fungi have crossed the CleanTechnica radar as a potential biofuel resource, a packaging and insulation material, and a plant-based alternative to animal-derived leather. The idea of making sustainable concrete-type blocks from fungi has also been percolating for several years.
In January, for example, NASA published a proposal from the University of Nebraska that describes how sustainable buildings could be grown on Mars by, combining the masonry skills of fungi and cyanobacteria.
“This research proposes that, rather than shipping prefabricated outfitting elements to Mars, habitat outfitting can be realized by insitu construction using cyanobacteria and fungi as building agents,” explains Congrui Grace Jin, an assistant professor at the school’s College of Engineering, with in situ meaning that the blocks would be fabricated at the construction site.
The self-repairing bio-material would incorporate native soil, aka regolith, from the planet’s surface to grow homemade building blocks.
“Synthetic biology toolkits will be employed to create a synthetic lichen system, composed of diazotrophic cyanobacteria and filamentous fungi, to produce abundant biominerals (calcium carbonate) and biopolymers, which will glue Martian regolith into consolidated building blocks,” Jin added.
Free-Form Sustainable Buildings From Fungi: The Proof Is In The Paste
Building blocks and other fungi-based forms are typically created within molds. The process involves mixing spores from mycelium, the underground structure from which mushrooms sprout, with grains or other food sources. After spending time in a dark, fungi-friendly environment, the mold is filled with a dense, tightly bound material that can be released and dried into a hard block or other shape.
Mycocrete goes off in a free-form direction. It is created in a flexible, knitted platform developed by the Living Textiles Research Group, under the umbrella of the Hub for Biotechnology and the Built Environment at the UK’s University of Newcastle.
The process is described in detail in the article, “BioKnit: development of mycelium paste for use with permanent textile formwork,” published in the journal Frontiers in Bioengineering and Biotechnology. Newcastle also helpfully provides background material on its website and in a press release.
“Our ambition is to transform the look, feel and wellbeing of architectural spaces using mycelium in combination with biobased materials such as wool, sawdust and cellulose,” explains Dr Jane Scott of Newcastle University, who is the corresponding author of the paper.
As described by Dr. Scott, fungi-based blocks barely tap the surface of the potential for creating sustainable buildings with mycelium.
One constraint with rigid, block-type molds is providing enough oxygen for the mycelium to grow. A textile mold can solve that problem by offering a flexible, oxygen-permeable surface, but that leads to other problems. It is difficult to make a flexible textile keep a desired shape while the mycelium fills it. Flexibility also makes a textile mold difficult to pack.
To help solve the new problems, the team decided to make knitted molds in the shape of tubes, which can be hung on a frame to maintain their shape while filling.
If you’re wondering why knitting and not weaving, that’s a good question. “Knitting is an incredibly versatile 3D manufacturing system,” Dr. Scott explained. “The major advantage of knitting technology compared to other textile processes is the ability to knit 3D structures and forms with no seams and no waste.”
How To Knit Sustainable Buildings
The team decided to inject their mycelium paste into the knitted tubes with an injection gun, in order to achieve consistent packing. That resulted in another challenge. The paste had to be free-flowing, but not too watery. They settled on a combination of mycelium, paper powder, paper fiber clumps, water, glycerin, and xanthan gum, a thickener commonly used in food production, among other industries.
The team tested their method on tubes knitted from merino wool and compared the results with other mycelium composite approaches. They found that their samples outperformed other composites on stress tests, and shrank less upon drying. That’s important, as shrinkage could impact the potential for mass production.
Don’t hold your breath for the fungi-knitted sustainable buildings of the future just yet. Dr. Scott advises that integrating fungi-friendly textile manufacture into the sustainable buildings industry is not just a matter of developing the right mycelium compound. It also means retooling factories to and developing the necessary equipment for large scale construction projects.
However, you might see mycocrete popping up in demonstration projects sometime soon. The team’s “BioKnit” prototype structure illustrates how sustainable building design can deploy alternative materials that solve conventional construction problems. They created BioKnit as a one-piece, freestanding project that requires no joining, which eliminates the potential for weak spots that can occur in conventional construction.
Do-It-Yourself Sustainable Buildings, Eventually
By way of demonstrating readiness for action, BioKnit is not a lab-created hothouse flower. The team grew it as a single piece in the “OME,” an experimental house on the Newcastle campus, using a knitted form made of wool and linen.
At 1.8 meters high and 2 meters in diameter, BioKnit is a relatively small structure, but it illustrates some important features of mycocrete.
“The prototype demonstrates that the mycelium-knit composite has sufficient compressive strength to support a free-standing, slender vault,” the University of Newcastle explains.
If you’re thinking of DIY-ing one of these at home, you’ll have to consider how to optimize the curvature of the vault, which involves analyzing how textiles behave in tension. That may be easier than it sounds. All you have to do is assemble the structure while soft, and hang it up to form a sort of suspended hammock.
“This approach employs the understanding utilised in many architectural vernaculars that the curve of a hanging cable, when inverted, provides an optimal arch structure which works entirely in compression,” Newcastle explains.
On the other hand, getting to the soft-structure step may require some additional expertise. The team deployed computer modeling to pregame for BioKnit, which included fine tuning to account for variations in the materials as well as physics simulations.
On the bright side, you might see grow-it-yourself sustainable buildings popping up in kit form, through the educational toys market. Here’s one example. If you can find others, drop us a note in the comment thread.
Come to think of it, LEGO has been scouting around for sustainable building materials to support its carbon neutral goals and its sustainable business profile. Recycled plastic seems to have the edge so far, but last year the company showcased an intricate, fan-created Mushroom House project under its LEGO Ideas initiative. Can fungi LEGO blocks be far behind?
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Photo: The BioKnit project demonstrates the potential for fungi to contribute to the sustainable buildings movement (photo courtesy of University of Newcastle).
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